Detachable arc controlling structure



P 1935. o. JENSEN EI'AL 1,996,112

DETACHABLE ARC CONTROLLING STRUCTURE Filed Jan. 18, 1932 I5 Sheets-Sheet l INVENTORS BY t 21 M1 59m 146 ATTORNEY April 2, 1935. o. JENSEN ETAL DETACHABLE ARC CONTROLLING STRUCTURE Filed Jan. 18, 1932 :s Sheets-Sheet 2 INVENTORS ATTORNEY April 2, 1935. O JENSEN ET AL 1,996,112

DETACHABLE ARC CONTROLLING STRUCTURE Filed Jan. 18, 1932 3 Sheets-Sheet 3 J INVENTORS ly. 311 (4% J W M24 cw ATTORNEY.

Patented Apr. 2, 1935 PATENT. OFFICE.

1,990,112 na'racmmnnanc con'raommc s was TRUC Otto Jensen and Knute Falck, Philadelphia, Pa., assignors to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of New Jersey Application January 18, 1932, Serial No. 587,190

10 Claims.

Our invention relates to electric switching mechanisms, and more particularly to removable arc controlling structure for switches and automatic circuit breakers.

In accordance with the invention, in switching mechanisms having a magnetic arc-controlling coil, for example, a blow-out coil, and are barrier structure for extinguishing or confining the arc across the switch contacts at the time of opening the switch, the blow-out coil is secured to the barrier, for example, enclosed therein, to comprise therewith a unitary structure, the coil having contact portions or terminals, preferably in predetermined positions with respect to each other, adapted detachably to engage complementary fixed contacts or clips, so that the blowout coil and barrier structure may readily be removed as a unit, to afford free access to the contacts and parts of the switch or circuit breaker for inspection, repair or replacement purposes. Preferably, and as shown, the barrier-coil unit is removable from the front of theswitch panel, access to the rear of the panel being unnecessary for this purpose.

The barrier-coil unit preferably, although not necessarily, comprises a blow-out coil molded or imbedded in refractory insulating material comprising, for example, asbestos and the like with suitable binder, which is pressed and hardened to the desired shape to form a, flame resistant barrier, the imbedded coil mechanically reenforcing the barrier to provide a rigid unitary structure.

The invention resides in the features of construction, combination, and arrangement hereinafter described and claimed.

To describe the invention, and for illustration of some of the various forms it may take, reference is had to the accompanying drawings, in which: V

Fig. 1 is a side elevational view of a circuit breaker having two removable barriers in accordance with the invention, and looking along the line ll of Fig. 2.

Fig. 2 is a front elevation of the circuit breaker, with both barriers in position.

Fig. 3 is a detail of panel terminal clips for the barriers.

Fig. 4 is a'view, partly in section, looking down upon one of the barriers in operating position.

Fig. 5 is a perspective view of one of the barriers removed from the circuit breaker.

Figs. 6 and 6a are side and end views, respectively, of the blow-out coil encased in the barrier Fig. 1.

Fig. 7 shows a removable barrier embodying a modified form of blow-out coil.

Figs. 8 and 8a. are side and end views, respectively, of the blow-out coil employed in Fig. 7.

Fig. 9 is a detail of the panel terminal clips of Fig. '7.

The maintenance of switch gear for controlling circuits carrying current for power, lighting, and other purposes, presents a problem of increasing importance as the service becomes .more severe and the requirements more exacting. Modern supply lines have a large capacity, so that the short circuit currents may rise to enormous values, and since each switch or circuit breaker must be able to clear its own circuit under such abnormal conditions, this, combined with increased frequency of operation, and exacting size and price conditions, make it essential to use all material at the highest duty and capacity consistent with good engineering practice.

These conditions impose the requirement of rugged simplicity and easy replacement of parts damaged in service. The most rapid deterioration is in the arcing area, and the inspection, replacement or repair of arcing tips must be made as easy as possible.

The embodiment of the invention illustrated involves an inductive blow-out coil enclosed or embedded in a barrier of moldable arc-resistant material, with electrical contact portions or terminals in recesses inthe base of the barrier, and which may readily be removed as a unit to give free access to the switch gear. Suitable means are provided for securing the barrier to the circuit breaker panel, and for removing it from the front of the panel. This also enables barriers to be readily renewed, and increases the space avail able for cleaning or changing the main and arcing contacts of the circuit breaker.

Referring now particularly to Figs. 1, 2 and 3, a supporting panel I of insulation, for example,

slate, has a bracket 2 secured thereto for supporting switch mechanism comprising an arm 3 carrying a main brush or bridge member 4 adapted to engage main contact terminals 5 and 5' to control an external circuit connected thereto by means of studs passing through to the back of the panel. The usual further appurtenances, such as electro-magnetic closing and tripping mechanism common in the art, is not shown. The secondary or auxiliary contact system comprises a shunt contact 6 secured to the upper part of terminal block I, a movable shunt contact I carried by arm a relatively fixed arcing contact l of carbon or other suitable material, and

a movable arcing contact Q carried by arm 3.

The main contact terminal 5 is connected to a metal bracket piece It having laterally extending arms terminating in switch clips or terminals l2, and the arcing contact support piece II also has switch clips or terminals l2. The terminals. [2- and. t2 fit into apertures or recesses l4 inthe barriers l3 disposed'on each side of the arcing contact system, as shown in Fig. 2,

the terminals engaging extensions, contact por tions or terminals l5, of a blow-outcoil 16, encased in each barrier. This particulararran'ge,--

ment permits the base of the barrier units 13 to lie flush against the supporting panel ;l ,providing a particularly rigid structure and minimize ing space requirements. .L'IJ; The type of blow-out coil illustrated is formed of a copper bar of any desired number of turns;

Figs. 6 and 6a. The adjacent parts =of, the coil,-

are insulated from each other, as by an enamel coating; or wrapping 0f insulation, and the coils are then placed in a mold and surrounded bya refractory insulating material whichispressed and hardened to :the desired shape; vI This ,rorms a rigid, flame-resistant barriercontaining an inductivecoil, with or without iron in the circuit, for'producing a magnetic field-suitably. to act on .the are occurring between the shunt contacts 8 and 9 when the main-switch orcircuit breaker :opens. I The coil also' provides a reinforcing structure for increasing themechanical strength of the barrier. Similarly, the. barrier secures the .3 two ends or terminals l 5 of the blow-out coil in fixed spaced relation with respect to each other :for

engagement with their complementary terminals -12, |2,"and, as seen 1,.the ends ofthe blow-out coil also' extend on opposite sides of therecess'es to provide a .firm anchorage. for the coilends;

Each of these-barriers is held against the panel by :a single'bolt all which is threaded into'a nut plate 18 (Fig. il secured to the back of the breaker panel; .Atbarl9.'of insulating materialcom nects the'twobolts across. the-front, tying the two barriers together and. providinga .mutualsupiport. The width of the barrier. base 20; Fig. 5, ensures a solid support, and theengagemcnt of the coil ends 15 with the panel clips l2, l2 makes rotation impossible. The recessed 1 portions I 4 of each barrier surround'and. enclose the termi- .nals l2, 1.2 when the barrier is .in operative position, and theterminals areftherebyprotected from arcing. occurring betweenthe arcing contactsBand 9." a: The panel terminals for'this barrier areillustrated in Fig. 3, which shows in perspective view the arrangement of these parts. The upper main terminal 5and-secondary or shunt terminal 6 are shown assembled to thecli'p plate It having laterally extending arms 10' terminating in blowout coilterminals l2. A clip plate 11, which car- -ries an arcing terminal support 2i, has corresponding laterally extending arms -'I!' "terminating in contacts]? for-connectionto-the upper ends of the respective blow-out coils; 'The plate I l I serves as a bridging member connecting the blow-out coils.- i

A detailed view or" the barrier mounting-and contact means is'shown' in Fig.4, This is a section in plan 'of'the recessedportion 1'4, showing 'the manner in which the'clips Her '12 engage the coil ends or terminals 1 5. Thecoil ends are beveled toiacilitate their entrance into the clips. These contacts carrythe current flowing through the arcing contacts, and during opening'and closcuit and low contact resistance. parts I2 are covered by a sheet or plate of insustrength and lightness.

ing movements of the circuit breaker, and particularly during short circuit or other abnormal conditions, the two clip. portions, i2, E2. of each contact are drawn toward each other during heavy current surges, because of the attraction between adjacent conductors in which current is flowing in the same direction. This maintains high'conta ct pressure ensuring continuous cir- The upper clip lation 23 to prevent an arc jumping to the body portionof -H and burning the metal. Each of the openings It has a recessed portion 5 lthrough which the arms in, l 1 and/or insulation 23 extend.

.A .perspective .view of one of the barriers is shown in Fig. .5. This drawing indicates a form which the barrier may take when designed for e A broad base portion 25 is provided to give lateral stability, while the 'outer portions may "comprise a webbed structure, the latter being reinforced-bythe blow-out coil.

A modified'form of the barrier is shown in Fig. 7. A half turn of copper 2t terminates in T shaped ends or terminalsZB (Figs. 8 and 8a,) within the recessesi l, theends of the T'headsbeing embedded in the barrier at opposite sides of the recessto firmly anchor the-terminal portions. The connection of this barrier-coil unit to a circuit breaker is necessarily different 'fromthat previously described, as it is essential to have current flowaround the loop in-a given direction', clockwise as viewed in Fig. '7, to force any'arc upward. This requires an arrangement of connections, such-as shown in Fig. 9. The terminal 5 and auxiliary terminal ii are shown secured to a connection plate 2G which is'carried up to the contact clips I 2" entering the recess 14 and engaging the coil ends or terminals 28 of the barriercoil unit. Mounted on the connection plate is an 1 insulating member 29 over which is secured the connection plate 36 having arms 25 for pivotally supporting the arcing contact 8,.the plate having laterally extending armsterrninating in lower contact clips'lz.

panel in the same manner as in the other modi- 'iication.

- While theblow-out coil is embedded in molded insulating material in the'forms illustrated, it will be understood that the coil may also be enclosed or embedded in sheets or boards of asbestos,

transite, or other suitable barrier material, in

*suchman'ner as to comprise therewith a unitary structure having substantially the advantages of the present invention.

It will further be understood that the blow out l coil'terminalelements-need not have the .knife blade' type of contact illustrated,.but mayIcomprise various other formsofcontact structure known in the art and suitable for the purpose, and

;that the meansfor securing the'barriers in place may comprise any suitable means other than that shown.

' It is also to be understood that the term blowout coilfis used in a generic sense,.a nd. embraces a coil or other structure of any. character for controlling arcing or flash-over, for ekample for plurality of, smaller s I What'we claim'isr 1 1.- In combination, a removable blow-out coil encased in a barrier of insulating m'aterialfthe This results in a reversal of 3 "connections'and causes current to flow in the *proper'direction to blow the arc upwardly. The {barrier-coil 'unit is detachably secured tothe,

barrier having recesses and the coil having terminals adapted to engage complementary contacts in the blow-out coil circuit, said terminals extending through said recesses and embedded in the material of the barrier on both sides of the recesses.

2. A panel, a blow-out coil and are barrier assembly removable therefrom and comprising a blow-cut coil embedded in a barrier of molded arc resist-ant material, the base of the barrier being normally positioned flush with said panel and having openings therein and the coil having terminals positioned in said openings, and complementary contacts supported from said panel and detachably engaging said terminals within said openings for connecting the coil in circuit.

3. In combination, a supporting panel having circuit-controlling contact structure mounted thereon, fixed contacts on the face of said panel connected to the circuit controlled by said contact structure, an arc controlling coil encased in a member of refractory insulating material, recesses in said member, said arc controlling coil having contact portions extending into said recesses, and adapted to engage said fixed contacts, and means for removably and positively securing said member of refractory insulating material to the panel accessible from the front of the panel.

4. In combination, a supporting panel, circuitcontrolling contact structure mounted on the face of said panel, fixed contacts on the face of said panel connected to the circuit controlled by said contact structure, a removable arc-controlling coil encased in a barrier of molded insulating material, said barrier having openings and the coil having terminals in said openings and adapted detachably to engage said contacts, the material of the barrier surrounding and enclosing said fixed contacts when the barrier is in operative position.

5. In combination, a circuit breaker having main and shunt contacts, conductive members respectively in circuit with said main and shunt contacts and having arms extending on either side of said shunt contacts, said arms having contacts in a blow-out coil circuit, and removable blow-out coils having terminals detachably engaging the contacts on said arms.

6. In combination, a circuit breaker having main and arcing contacts, conductive plate members respectively in circuit with said main and arcing contacts and having laterally extending arms on either side of said arcing contacts, said arms having contacts in a blow-out coil circuit, and removable blow-out coils disposed on either side of said arcing contacts and having terminals detachably engaging the contacts on said arms.

7. In combination with a circuit-controlling device, having a movable contact structure, individual blow-out units on opposite sides of the path of movement of said contact structure, each comprising an arc barrier and a blow-out element embedded therein, and a pair of stationary bridging members each including a pair of terminals detachably engaged by corresponding terminals of the blow-out elements of said individual units.

8. A circuit breaker comprising a panel, fixed and movable circuit-breaking contacts mounted on the face of said panel, auxiliary fixed contacts extending from said face of said panel to one side of said circuit-breaking contacts, and a removable blow-out unit comprising a barrier having a base flush with said panel and recesses therein to receive said auxiliary fixed contacts, and a coil enclosed in said barrier having terminals in said recess frictionally to engage said fixed contacts, said unit being removable by linear movement substantially normal to the face of said panel.

9. A circuit breaker comprising a panel having circuit-controlling contact structure mounted thereon, a pair of auxiliary contact structures supported from said panel and comprising a pair of elongated superimposed conductive strips insulated from each other, longitudinally spaced terminals individual to said auxiliary contact structures, and a blowout unit including a blowout coil of substantially a half turn having terminals connected to the spaced terminals of said contact structure.

10. A circuit breaker comprising a panel having circuit controlling contact structure mounted thereon, a pair of auxiliary contact structures supported from said panel and comprising a pair 

